如何在iPhone上使用Quartz显示文本？

发布于 2024-07-06 10:39:50 字数 480 浏览 5 评论 0原文

我一直在尝试使用 Quartz 上下文显示文本，但无论我尝试了什么，我都没有运气显示文本（尽管我能够显示各种其他 Quartz 对象）。有人知道我可能做错了什么吗？

例子：

-(void)drawRect:(CGRect)rect
{   
  // Drawing code
  CGContextRef  context = UIGraphicsGetCurrentContext();
  CGContextSelectFont(context, "Arial", 24, kCGEncodingFontSpecific);
  CGContextSetTextPosition(context,80,80);
  CGContextShowText(context, "hello", 6);
  //not even this works
  CGContextShowTextAtPoint(context, 1,1, "hello", 6);
}

原文

I've been trying to display text using a Quartz context, but no matter what I've tried I simply haven't had luck getting the text to display (I'm able to display all sorts of other Quartz objects though). Anybody knows what I might be doing wrong?

example:

-(void)drawRect:(CGRect)rect
{   
  // Drawing code
  CGContextRef  context = UIGraphicsGetCurrentContext();
  CGContextSelectFont(context, "Arial", 24, kCGEncodingFontSpecific);
  CGContextSetTextPosition(context,80,80);
  CGContextShowText(context, "hello", 6);
  //not even this works
  CGContextShowTextAtPoint(context, 1,1, "hello", 6);
}

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南笙 2024-07-13 10:39:50

好，我知道了。首先，将编码模式更改为 kCGEncodingMacRoman。其次，在其下方插入这一行：

CGContextSetTextMatrix(canvas, CGAffineTransformMake(1, 0, 0, -1, 0, 0));

这将设置文本的转换矩阵，以便正确绘制。如果您不添加该行，您的文本将上下颠倒并从后向前。不知道为什么这不是默认值。最后，确保您设置了正确的填充颜色。如果您忘记将背景颜色更改为文本颜色并最终得到白底白字，那么这是一个很容易犯的错误。

OK, I got it. First off, change your encoding mode to kCGEncodingMacRoman. Secondly, insert this line underneath it:

CGContextSetTextMatrix(canvas, CGAffineTransformMake(1, 0, 0, -1, 0, 0));

This sets the conversion matrix for text so that it is drawn correctly. If you don't put that line in, your text will be upside down and back to front. No idea why this wasn't the default. Finally, make sure you've set the right fill colour. It's an easy mistake to make if you forget to change from the backdrop colour to the text colour and end up with white-on-white text.

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假情假意假温柔 2024-07-13 10:39:50

这是我正在使用的代码片段。

UIColor *mainTextColor = [UIColor whiteColor];
[mainTextColor set];
drawTextLjust(@"Sample Text", 8, 50, 185, 18, 16);

和：

static void drawTextLjust(NSString* text, CGFloat y, CGFloat left, CGFloat right,
                          int maxFontSize, int minFontSize) {
    CGPoint point = CGPointMake(left, y);
    UIFont *font = [UIFont systemFontOfSize:maxFontSize];
    [text drawAtPoint:point forWidth:right - left withFont:font
       minFontSize:minFontSize actualFontSize:NULL
       lineBreakMode:UILineBreakModeTailTruncation
       baselineAdjustment:UIBaselineAdjustmentAlignBaselines];
}

Here is a fragment of code that I'm using.

UIColor *mainTextColor = [UIColor whiteColor];
[mainTextColor set];
drawTextLjust(@"Sample Text", 8, 50, 185, 18, 16);

And:

static void drawTextLjust(NSString* text, CGFloat y, CGFloat left, CGFloat right,
                          int maxFontSize, int minFontSize) {
    CGPoint point = CGPointMake(left, y);
    UIFont *font = [UIFont systemFontOfSize:maxFontSize];
    [text drawAtPoint:point forWidth:right - left withFont:font
       minFontSize:minFontSize actualFontSize:NULL
       lineBreakMode:UILineBreakModeTailTruncation
       baselineAdjustment:UIBaselineAdjustmentAlignBaselines];
}

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